Method of insolubilizing artificial filaments of vegetable protein



Aug. 28, 1951 R. CAMPBELL ET AL 2,565,908

METHOD OF INSOLUBILIZING ARTIFICIAL FILAMENTS OF VEGETABLE PROTEIN Filed July 28, 1948 Patented Aug. 28, 19 51 i METHOD OF INSOLUBILIZING ARTIFICIAL FILAMENTS OF VEGETABLE PROTEIN Ray Campbell, Ardrossan, .William E. Tetlow, Saltcoats, and Robin H. K. Thomson, Fairlie, Scotland, assignors to Imperial Chemical Industries Limited, a corporation of Great Britain Application July 28, 1948, Serial No. 41,126 In Great Britain October 6, 1947 6 Claims. (Cl. 8127.6)

The present invention relates to a. new or improved method for insolubilising artificial filaments, threads, fibres and the like filamentary products spun from protein solutions, and more particularly those obtained by the spinning of solutions of vegetable seed globulins, for instance peanut protein, or phospho-proteins, for instance casein, in aqueous alkaline or other suitable aqueous solvent media into suitable acidified saline coagulating baths. Sodium sulphate solutions slightly acidified with sulphuric acid are in practice most advantageously used as the coagulating baths.

The filamentary products emerging from the coagulating bath are still easily soluble in dilute saline solutions. They can be rendered insoluble in dilute saline solutions and in cold water by a hardening treatment with formaldehyde, but in order to render the filamentary products capable of ordinary textile application they must be rendered capable of withstanding also the action of boiling water, so that they can be dried oif without sticking together, and further the action of hot dilute acid solutions such as are used in the application of acid wool dyes and of hot dilute alkaline solutions such as are used in laundering.

While a number of processes for insolubilising protein artificial filamentary products for this purpose have been described it is believed that the best insolubilisation and the best physical properties and separation of the individual filaments or the like from one another have hitherto been attained by the use of a strongly saline solution of formaldehyde containing not less than 30 parts sodium chloride per 100 parts water by weight, acidified with suificient hydrochloric acid or sulphuric acid to bring the pH below 1. Such a bath is described in British Specification No. 513,910. The coagulating solution associated with the filaments or the like emerging from the coagulating bath is usually rinsed away from them by treating them with sodium chloride brine before introducing them into the aforementioned insolubilising solution.

The insolubilisation with the aforesaid acidified brine formaldehyde solution however necessitates the maintenance of the filamentary prodnet in contact with the insolubilising solution for a prolonged period, even at raised temperatures, for instance 18 hours at 38 C., and the period of treatment cannot be reduced by the employment of considerably higher temperatures, since the loose filaments, threads, fibres tend to clump together at such higher temperatures instead of remaining open. 1

2 In British Patent Specification No. 597,497, which corresponds to the co-pending U. S. application, Ser. No. 681,153, now U. S. Patent No. 2,533,297, there is claimed a method of insolubilising artificial filamentary products obtained by the spinning of solutions of vegetable seed globulins, for instance, peanut proteins, or phospho-proteins, for instance casein, in aqueou a1- kaline or other suitable aqueous solvent media into suitable acidified saline coagulating baths by treating the said filamentary products in an aqueous formaldehyde bath saturated to both sodium chloride and sodium sulphate or to both sodium chloride and magnesium sulphate, at a pH of 4 to 6 and at a temperature not exceeding C. and thereafter treating the filamentary product in an aqueous formaldehyde bath strongly acidified with sulphuric acid, that is. containing at least 175 grams of sulphuric acid per litre of solution, and saturated with sodium sulphate or magnesium sulphate at the temperature employed, the said strongly acidified formaldehyde bath being at a raised temperature.

It is stated therein that if the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and sodium sulphate then the strongly acidified formaldehyde bath is preferably saturated with sodium sulphate, while if the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and magnesium sulphate then the strongly acidified formaldehyde bath is preferably saturated with magnesium sulphate.

It is also stated therein that if the temperature of the first bath is 50 C. a period of about five minutes is sufficient and that if the temperature is about 40 C. 8 minutes to 15 minutes are required. It is also stated that if the temperature of the second bath is about C. the time required for treatment is usually about 10 to 15 minutes.

The object of the present invention is to provide a simple and efiicient method of insolubilising a continuous travelling tow of unhardened protein artificial filamentary material.

It has now been found that if the formaldehyde solution at pH 4 to 6 saturated with sodium chloride is at a temperature between 60-70 C. and the treatment is carried out while the tow is passed through a current of the solution in a length of tubing of suitable diameter preferably arranged as a coil of helical form that the solution need not be saturated with respect to sodium sulphate and that the time required for treatment is only about to 1 minute. It has also been found that if the aqueous formaldee hyde solution strongly acidified with sulphuric:

acid, that is, containing at least 175 grams of sulphuric acid per litre of solution, and saturated with sodium sulphate or magnesium sulphate at the temperature employed as used in the method of British Patent No. 597,497 is at a temperature of about 95 C. and the treatment is likewise carried out in a current of this solution while passing through a helical tube that the time of treatment required is only about 2 minutes.

According to the present invention the method of insolubilising artificial filamentary products obtained by the spinning of solution of vegetable seed globulins, for instance, peanut proteins, or phospho-protein, for instance, casein in aqueous alkaline or other aqueous solvent media into acidified saline coagulating baths comprises passing the filamentary products and an aqueous formaldehyde solution saturated to sodium chloride and containing sodium sulphate or magnesium sulphate at a pH of 4 to 6 and at a temperature preferably in the neighbourhood of about 70 C. through a tubular passage preferably anranged as a coil of helical form and thereafter passing the thus treated filamentary product and an aqueous formaldehyde solution strongly acidified with sulphuric acid and saturated with sodium sulphate or magnesium sulphate at the temperature employed, the said strongly acidified formaldehyde solution being at raised temperature preferably in the neighbourhood of about 95 0., through another tubular passage preferably arranged as a coil of helicalform.

The tubular passage is preferably likewise of narrow diameterrand if it is straight the treating liquid is passed therethrough preferably under such conditions as to be in turbulent flow. The treating liquid is always to flow through the tubular passage at least at such speed as to advance the filamentary products through the said passage.

The tubular passag .can .be completely immersed in a bath of water of such temperature as to maintain the liquor circulating in the pas-- sage at the stated temperature and so prevent cooling and consequent crystallisation of salts whichmight result in damage to the fibre.

The tow-of filaments is preferably carried into the tubular passage by having a funnel fitted on tothe entrance to the passage. liquor is directed into this funnel, flowing by gravity through the said tubular passage. The flow 'of liquor from the funnel-to the tubular passage provides the necessary impetus to take the tow .of filaments into the tubular passage. It has been found advantageous to fit an overflow pipe from the funnel to the treating liquor-circulating tank in order to maintain steady flow conditions in the tubular passage.

The invention is further illustrated byythe following example inwhich the parts are parts by weight except where otherwise indicated andwith reference to the accompanyin diagrammatic drawing.

Example A maturedcaustic soda solution of groundnut globulin prepared from a solution containing 25 parts peanut globulin, 1.25 parts .sodium hydroxide, 1.0 part sodium sulphiteand 172.75 parts water is extruded through a spinneret 'i into a coagulating bathi containing'ZGO gm./l.sodium sulphate and gm./l. sulphuric acid. The resulting tow of filaments 3 is taken up on godets 4 having .a peripheral speed of 30 :metres per minute r and stretched 2 by passing 1 on "to. godets .;5

The treating havin a peripheral speed or metres per minute.

The tow 3 is then led under tension to a godet 6 situated .vertically above the centre line of the trough of a ,ring trough i in accordance with the method claimed in co-pending U. S. application Serial No. 2,246, filed January 14, 1948, now Patent No. 2,555,065, through a reciprocating spacing device .8 at least 3 feet above the surface of the liquor in the trough and so into the trough in which the fibre is deposited in a zig-zag manner. This ring-trough consists of a solid centre section 2 feet in diameter with a trough 0.5 foot wide and 4 inches deep outside but integrally joined to it and is made of mild steel. The ring trough contains abase of wire gauze 9 and revolves in a circular trough i0, 3 feet 4 inches external diameter, 1 foot 7 /2 inches internal diameter and 6" deep, also of mild steel, fitted with an adjustable weir so that the height of liquor in the trough maybe varied at will. The ring-trough contains a saturated solution of sodium chloride at a temperature of 20 C. and at a pH M50. The tow 3 sinks on to the base of the trough i and is carried round with the trough I which revolves one in 4% minutes. Thus the time of immersion of the tow 3 in the acidified saturated sodium chloride solution is 4 ,42 minutes. The tow 3 is taken up vnot less than 3 from the fibre inlet and then stretched between two .godets ll and I2 whose peripheral speeds are 35 and 52 metres per minute respectively.

.After stretching, the tow 3 passes over a godet l3 placed vertically above the centre line of the entry id of a vertically positioned helical coil J5 of -120 .feet in length and of 4 feet diameter. Through this coil there passes a solution saturated yvith respect to sodium chloride at 770 and containing 20 grams of sodium sulphate per litre sand 2% of formaldehyde. The temperature of this solution is Caand the pH 5.0. The time of passage of {the tow 3 through gthis coil is {/2 to 1 .minute. The tow 3 is .picked up over ars det i6 arranged vertically above the exit of the vertically positioned coil. The tow 3 is stretched between two godets H, 18 whose peripheral speeds are '40 and +15 metres/minute. The tow ,3 then enters .th oughentry i9 another vertically .positioned coil '20 of length 150 feet and of diameter 4 feet through which flows a treating liquor consisting of saturated sodium sulphate at C., 275 gramsperlitre sulphuric acid and 2% formaldehyde. The temperature of this liquor is 95 and the pH is less than 0. The time of passage of the tow through thiscoil 20 is 12 minutes. On leaving .the outlet-of this second coil 20 the tow 3 .is'taken up over a godet 2! and washed and. dried by .any known method.

';We claim:

1. A method for reducing the time of treatmentrequired for insolubilizing artificial filamenta-ry products obtained by spinning aqueous solutions of proteins selected from the group consisting of .vegetableseed globulins and phosphoproteins into acidified saline coagulating baths which comprises passing the -coagulated filamentary products through a confined areaand in direct contact with a stream of an aqueous formaldehyde solutionhaving a temperature of from :aboutfiil" .Cxto 70 C. and a pH of 4 to fi, saidsolutionbeing saturated with sodium chloride and-containing a sulphate from theg-roup consisting of sodium sulph e an ma nes u 5.111- ph d t te pass n the thus treated filamentary products through another confined area and in direct contact with a stream of a second aqueousfformaldehyde solutionhaving a temperature of about 95 C., said last named aqueous formaldehyde solution containing at least 175 grams per'litre of sulphuric acid; and being saturated; at the temperature employed, with a sulphate fromthe group consisting fof sodium sulphate and magnesium sulphate.

2. The method of claim 1 wherein at least one of said confined areas is of helical form.

3. The method of claim 1 wherein the streams of the aqueous formaldehyde solutions fiow in a turbulent manner.

4. The method of claim 1 wherein said filamentary products are in the form of a continuous tow.

5. The method of claim 1 wherein said protein is peanut protein.

6. A method for reducing the time 'of treatment required'for insolubilizing a continuous tow of artificial filamentary products obtained by spinning aqueous solutions of proteins selected from the group consisting of vegetable seed globulins and phospho-proteins into acidified saline coagulating baths which comprises passing said tow in an' untensioned condition through a confined area for from about to 1 minute and in direct contact with a stream of an aqueous formaldehyde solution at a temperature of from about 60 C. to 70 C. having a pH of 4 to 6, said solution being saturated with sodium chloride and containing a sulphate from the group consisting of sodium sulphate and magnesium sulphate, and thereafter passing the thus treated tow in an untensioned condition through another confined area for about two minutes and in direct contact with a stream of a second aqueous form-P aldehyde solution at a temperature of about C.,'said last-named aqueous formaldehyde solution containing at least grams per litre of sulphuric acid and being saturated, at the temperature employed, with a sulphate from the group consisting of sodium sulphate and magnesium sulphate.

RAY CAMPBELL.

WILLIAM E. TETLOW.

ROBIN H. K. THOMSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,372,622 Wormell Mar. 27, 1945 2,409,475 Cline Oct. 15, 1946 2,428,603 Atwood Oct. '7, 1947 2,429,214 Biehn et al. Oct. 21, 1947 FOREIGN PATENTS Number Country Date 543,586 Great Britain Mar. 4, 1942 

1. A METHOD FOR REDUCING THE TIME OF TREATMENT REQUIRED FOR INSOLUBILIZING ARTIFICAL FILAMENTARY PRODUCTS OBTAINED BY SPINNING AQUEOUS SOLUTIONS OF PROTEINS SELECTED FROM THE GROUP CONSISTING OF VEGETABLE SEED GLOBULINS AND PHOSPHOPROTEINS INTO ACIDIFIED SALINE COAGULATING BATHS WHICH COMPRISES PASSING THE COAGULATED FILAMENTARY PRODUCTS THROUGH A CONFINED AREA AND IN DIRECT CONTACT WITH A STREAM OF AN AQUEOUS FORMALDEHYDE SOLUTION HAVING A TEMPERATURE OF FROM ABOUT 60* C. TO 70* C. AND A PH OF 4 TO 6, SAID SOLUTION BEING SATURATED WITH SODIUM CHLORIDE AND CONTAINING A SULPHATE FROM THE GROUP CONSISTING OF SODIUM SULPHATE AND MAGNESIUM SULPHATE, AND THEREAFTER PASSING THE THUS TREATED FILAMENTARY PRODUCTS THROUGH ANOTHER CONFINED AREA AND IN DIRECT CONTACT WITH A STREAM OF A SECOND AQUEOUS FORMALDEHYDE SOLUTION HAVING A TEMPERATURE OF ABOUT 95* C., SAID LAST NAMED AQUEOUS FORMALDEHYDE SOLUTION CONTAINING AT LEAST 175 GRAMS PER LITRE OF SULPHURIC ACID AND BEING SATURATED, AT THE TEMPERATURE EMPLOYED, WITH A SULPHATE FROM THE GROUP CONSISTING OF SODIUM SULPHATE AND MAGNESIUM SULPHATE. 